1. Field of the Invention
The present invention relates to a radiant device, and preferably an infrared radiator, with at least one radiant source oriented in the direction of the long axis of an envelope tube which is sealed at both ends, with a metal, electrical connecting part at each end of the envelope tube and, inside the envelope tube, with at least one elastic intermediate part which absorbs the length changes of the radiant source and which is firmly joined at one end to an electrical connecting part and at the other end to the radiant source.
2. Description of the Background
Such radiant devices or radiators are generally known and are described, for example in British Patent Application GB A 2233150. The infrared radiant source presented in that application is provided with an envelope tube of material transparent to infrared radiation, which tube contains an electrical conductor formed from carbon fibers connected to an electrical power supply. The envelope tube is sealed at its ends and either can be evacuated or can be filled with a gas such as argon. There are thereby obtained radiant sources with rapid response behavior, which can be operated at temperatures above 1200xc2x0 C. In the transition region between the electrical conductor and the connecting pins led out from the envelope tube at the ends thereof there is inserted, inside the envelope tube, a helically wound metal wire conductor, in order to compensate for the different length expansions, especially of the conductor, inside the envelope tube.
German Patent Application DE A 14419285 (equivalent to U.S. Pat. No. 5,567,951) also describes a radiant device, particularly an infrared radiator, with at least one flat-form radiant source. The radiant source is a carbon ribbon, which is disposed as a plurality of contiguous partial sections, the partial sections being held at their ends in supports, at least the first and last of which are formed as contacts. This radiant device is resistant to temperature fluctuations even over a prolonged time, and it also exhibits low inertia.
Starting from the prior art described above, the object of the present invention is to design a radiant device of the type described above in such a way that it can be constructed in particular with small fluorescent-tube or envelope-tube diameters, for example, with inside diameters in a range smaller than 12 mm, while at the same time ensuring that length changes in the radiant source can be compensated for.
This object is achieved in a radiant device of the type described above, wherein the intermediate part comprises a molybdenum sheet provided with at least one folding portion having two kink points perpendicular to the long axis.